Leucocoprinus birnbaumii

Description
Mushroom Identification
Look-Alikes
Getting Rid of Leucocoprinus birnbaumii in Houseplants
History
Synonyms and Varieties
Video

Description

Leucocoprinus birnbaumii originally comes from tropical forests. The first description was based on specimens in Sri Lanka. In the meantime, due to the trade in orchid soil, it has spread almost worldwide and often grows in houseplants. This little yellow parasol mushroom can be dangerous if eaten, it can cause a very unpleasant stomach upset. The main distinguishing features are a bright yellow, striate, dry, powdery to scaly cap; free crowded yellow gills; a yellow, dry, powdery stem with a yellow ring; a white spore print; grows in flower pots or planter boxes. The life cycle is simple, it feeds on the surrounding humus, disappears as quickly as it came, and as soon as the conditions of humidity and heat are met, it will reappear. The smell is described as indistinct or sometimes mushroomy.

The Leucocoprinus birnbaumii mushroom is poisonous to dogs or cats only in very large quantities. North Carolina State University classifies the species as having medium severity poison characteristics whilst the University of Massachusetts Amherst says that the level of toxicity is simply unknown at present.

Leucocoprinus birnbaumii doesn't have any hallucinogenic effect. Also, it doesn't harm living plants.

Common names: Flowerpot Parasol, Lemon Yellow Lepiota, Yellow Pleated Parasol, Plantpot Dapperling, Yellow Spirit Umbrella, Goudgele Plooiparasol (Netherlands), Keltaukonsieni (Finnish), Gelber Faltenschirmling (German), Bedla cibulkotřenná (Czech Republic), Gulfnokket Paraplyhatt (Norway), Gul Veckskivling (Sweden).

Mushroom Identification

Cap

0.98 to 1.97 inches (2.5 to 5 cm) across; oval to egg-shaped when young, becoming broadly conical, broadly convex, or bell-shaped; dry; powdery to finely scaly; the margin lined or grooved nearly to the center by maturity; bright to pale yellow, often with a darker (but not brown) center.
Gills

Free from the stem; crowded; short-gills frequent; pale yellow to yellow.
Stem

1.18 to 3.94 inches (3 to 10 cm) long; 0.08 to 0.20 inches (2 to 5 mm) thick; more or less equal above a slightly swollen base; dry; bald or powdery; with a fragile, bracelet-like, yellow ring that sometimes disappears; basal mycelium pale yellow.
Flesh

Whitish to yellowish; very thin.
Spore Print

White.
Habitat

Saprobic mushroom; growing alone, gregariously, or clustered in flower pots, greenhouses, and so on—or, in warm conditions, outside in gardens, lawns, and other cultivated areas (often around stumps). Also growing in hardwood and conifer forests, especially in disturbed ground areas (path sides, etc.). Fruits outdoors in summer and indoors all year round. It is widely distributed in North America.
Microscopic Features:

Spores 8–12 x 5–7 µm (occasionally shorter, 7–9 x 5–6 µm); ellipsoid to slightly amygdaliform, with a 1–2 µm pore at one end; smooth; thick-walled; hyaline in KOH; dextrinoid. Basidioles inflated, brachybasidiole-like. Cheilocystidia to about 50 x 15 µm; ventricose; rostrate; thin-walled; smooth; hyaline in KOH. Pleurocystidia absent. Pileipellis a cutis of elements 5–10 µm wide; terminal cells cylindric with rounded apices. Floccose material on cap surface composed of inflated, subglobose to pyriform elements 15–25 µm across.

Look-Alikes

Bolbitius titubans

Also yellow and striate, but has a slimy-viscid cap.
Leucocoprinus flavescens

Also small-spored and has a pale yellowish to white cap with a brownish centre.
Leucocoprinus brunneoluteus

Similar yellow dapperling mushroom from South America with a pronounced brown umbo and thin, fragile flesh.
Leucoagaricus sulphurellus

Similar yellow species occur in the Caribbean area, but have gills that bruise bright blue-green.
Leucocoprinus tricolor

Has a brown cap center, pale yellow colors, and a chrome yellow stem base.
Lepiota fragilissimus

Has an extremely thin cap and pale gills.
Leucocoprinus straminellus

Differs in less vivid yellow coloration and spore size (5-7 x 4-6 µm).
Lepiota citrophylla

Deadly poisonous. Does not have the typical wrinkled, ridged cap edge and only a fibrous, flaky ring zone.
Leucoprinus cepaestipes

Has a white, striate cap and fruits outdoors on well-rotted wood chips or in the grass under conifers.

Getting Rid of Leucocoprinus birnbaumii in Houseplants

The mushrooms are not known to harm plants either and likely came in with the potting soil.

Once the soil becomes infected, it is very difficult to remove the spores and fungus that causes the mushrooms, but there are a few things you can try:

Remove the caps

By removing the caps as soon as possible, you are removing the source of the spores which result in mushrooms growing in houseplant soil. This will also help keep mushrooms out of your other houseplants.
Scrape the soil

Scraping the top 2 inches of soil off the houseplants pot and replacing it may help, but the fungus may regrow and the mushrooms will return.
Change the soil

Changing the soil may possibly help with getting rid of mushrooms. One of the problems is that it is not healthy to remove all of the soil from a plant’s roots (through washing or rinsing) and the fungus may still be present and regrow from the soil left on the roots of the houseplant.
Drench the soil with a fungicide

Drenching the houseplant’s soil with a fungicide may help with eliminating mushrooms in houseplants, but again, if not all of the fungus is killed, the mushrooms will return. You may need to try this treatment several times before the fungus is killed completely.
Change the conditions

If the air is less humid, the soil-less moist or the temperature less warm, this will reduce the number of mushrooms that appear. Unfortunately, the conditions that are ideal for mushrooms are also ideal for most houseplants, so by changing the conditions, you may harm the houseplant itself.

History

In 1785 Yorkshire mycologist James Bolton described this species and named it Agaricus luteus. In 1839 the Czech mycologist August Corda described the same species, based on specimens that had been found in a greenhouse by a garden inspector named Birnbaum - hence the specific epithet birnbaumii. In 1961 Rolf Singer's transfer this species to the genus Leucocoprinus with the new scientific name Leucocoprinus birnbaumii.

Leucocoprinus is derived from the Greek leucos (meaning white) and coprinus, a name for the genus that until recently included all fungi commonly known as ink caps.

The specific epithet birnbaumii honors a Czech gardener who found this mushroom growing in a hothouse in 1839.

Synonyms and Varieties

Agaricus birnbaumii Corda, 1839
Agaricus aureus F.M. Bailey 1913
Agaricus birnbaumii Corda
Agaricus cepaestipes Schnizlein (1851), in Sturm, Deutschlands flora, Abt. III, die pilze Deutschlands, 6(32), p. 2, tab. 1
Agaricus cepaestipes var. flos-sulphurisSchnizlein (1867), in Oudemans, Archives néerlandaises des sciences exactes et naturelles, série 1, 2, p. 19
Agaricus cepaestipes var. ß luteus Persoon (1801), Synopsis methodica fungorum, p. 416
Agaricus cepistipes sensu Sowerby
Agaricus cepistipes var. luteus Bolton
Agaricus citrinus Passerini (1872), Nuovo giornale botanico italiano, serie 1, 4, p. 82
Agaricus flammula Albertini & Schweinitz (1805), Conspectus fungorum in Lusatiae superioris, p. 149
Agaricus flos-sulphuris Schnizl., 1851
Agaricus luteus Bolton (1788), An history of fungusses growing about Halifax, 2, p. 50, tab. 50
Agaricus vitellinus J.F. Gmelin (1792), Systema naturae, Edn 13, 2, p. 1400
Bolbitius birnbaumii (Corda) Saccardo & Traverso (1910), Sylloge fungorum omnium hucusque cognitorum, 19, p. 151
Lepiota aurea Massee (1912), Bulletin of miscellaneous information - Royal botanic Gardens, Kew, 1912(4), p. 189
Lepiota birnbaumii
Lepiota cepaestipes var. flos-sulphuris(Schnizlein) Rick (1907), Brotéria, revista de sciencias naturaes do Collegio de S. Fiel, serie botânica, 6(2), p. 69
Lepiota cepaestipes var. lutea(Persoon) Quélet (1886), Enchiridion fungorum in Europa media et praesertim in Gallia vigentium, p. 7
Lepiota cepistipes var. lutea (Bolton) Sacc.
Lepiota cepistipes var. luteus (Sow. ex Merat.) Kumm. s. Lange
Lepiota coprinoides Beeli, 1936
Lepiota flammula (Albertini & Schweinitz) Gillet (1874), Les hyménomycètes, ou description de tous les champignons (fungi) qui croissent en France, p. 63
Lepiota flos-sulphuris (Schnizlein) Spegazzini (1899) [1898], Anales del Museo nacional de Buenos Aires, serie 2, 3, p. 89
Lepiota lutea (Persoon) Quélet (1888), Flore mycologique de la France et des pays limitrophes, p. 298
Lepiota lutea var. aurantiofloccosa A.H. Sm. & P.M. Rea
Lepiota lutea var. lutea (Bolton) Mattir.
Lepiota pseudolicmophora Rea (1922), British Basidiomycetae, a handbook to the larger british fungi, p. 74
Leucoagaricus luteus (Sow. ex Fr.) Locq.
Leucocoprinus birnbaumii (Corda) Singer (1962) [1961], Sydowia : Annales mycologici, editi in notitiam scientiae mycologicae universalis, series II, 15(1-6), p. 67
Leucocoprinus birnbaumii var. birnbaumii (Corda) Singer
Leucocoprinus birnbaumii var. salvadorianus Raithelh.
Leucocoprinus flos-sulfuris (Schnizlein) Singer
Leucocoprinus flos-sulphuris (Schnizlein) Cejp (1948), Ceská mykologie, 2(3), p. 78
Leucocoprinus luteus (Persoon) Locquin (1943), Bulletin mensuel de la Société linnéenne de Lyon, 12, p. 41
Pholiota flammula (Albertini & Schweinitz) Migula (1912), Kryptogamen-flora von Deutschland, Österreich und der Schweiz, Band III. Pilze, 2(2), p. 538